Synchronous electron motor



Jan. 12, 1937. A. B. DU MbNT SYNCHRONOUS ELECTRON MOTOR Original FiledJan. 31. 1950 INVENTOR. DuMan 1' BY 9 t ATTORNEY8.

Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE SYNCHRONOUS ELECTRONMoron Allen B. Du Mont, Upper Montclair, N. 8., as-

signor to Allen B. Du Mont Laboratories, Inc., Upper Montclair, N. 1., acorporation of Delaware Original application January 31, 1930, SerialNo.

Divided and this application March 25, 1935, Serial No. 12,854

90mins. (cl. 172-36) caused to travel at high velocity towards andstrike a movable member under the influence of an electrode maintainedat a positive potential with respect to the motor surface. In thisdevice the construction is such that when energized by alternatingcurrent the movable member is caused to operate at synchronous speed. 1

The invention consists of many other objects which are obtained by meansof the structure 20 disclosed in full detail below.

This invention resides substantially in the combination, construction,arrangement and relative location of parts, all as will be fully setforth in the following specification in conjunction with .9 the attacheddrawing and pointed out in the appended claims.

This application is a division of my copending application Serial No.425,025, filed January 31, 1930 issued as Patent No. 1,999,407 and dated30 April 30, 1935. a

In the drawing,

Figure 1 is a combined vertical cross-sectional view and sideelevational view of one form of device in accordance with thisinvention;

Fig. 3 is a diagrammatic illustration of the cir-- cult connectionsemployed to attain the object of this invention; 3 Fig. 4 is adiagrammatic view ofa slightly modified arrangement in accordance withthe principles of this invention;

Fig. illustrates curves representing the rectifying action of themovable member or rotor. 45 Referring to Figs. 1 and 2, the devicecomprises an evacuated envelope l of any desired shape and configurationto serve as an enclosure for'the other parts of the mechanism. While theenvelope is shown as having the shape usually employed for audions, itwill be understood that any other shape particularly adapted for thepurpose may be employed. The envelope is provided with a reentrant stem2having a press 2' in which the various elements of the combination are55 mounted. At the center of the device is the cathode comprising atubular or rod like body 3 of insulating material having a pair oflongitudinal bores extending entirely therethrough. This rod 3 isenclosed within a metal bore or sleeve 4 upon the surface of which isapplied a coating 5 of 5 any well known material capable of emittinglarge quantities of electrons when heated. Mounted within the bores ofthe rod is the heater or filament 6 by means of which the electron surface is rendered active. As will be apparent to 10 those skilled in theart, this construction exemplifies one well known form of indirectlyheated cathode structure. It is of course apparent to those skilled inthe art that any equivalent cathode structure may be employed withoutdeparture from the scope of this invention. The ends I and 8 of theheater 6 are connect- ,,ed respectively to the lead-in wires 9 and inwhich are sealed in the press 2' and which are connected to theterminals of the secondary of a transformer l I energized from anysuitable alternating current source. The cathode assembly is supportedfrom the press by means of the rods or wires l2 and i3 which arelikewise sealed in thepress. At i6 are illustrated four plate-like 26members of arcuate cross section lying substantially upon thecircumference of a cylinder concentric with the cathode assembly. Theseplates iii are comparable to the anode of the usual audion, and aresupported from the press by 80 means of rods l5 and I! which are sealedtherein.

As will be pointed out later, the four plates l6 are electricallyconnected together, and by means of one of the supporting rods l5 'tothe secondary of a transformer which supplies an alternating 86current'potential to the plates. The other terminal of the secondary ofthis transformer is connected by a wire to the support l2 which in turnis electrically, as well as mechanically connected to the cathode sleeve4. 40

Likewise sealed in the press 2 are a pair of supporting rods orstandards I8 which are joined at their upperlends by means of a bearingplate l9 which provides a rotatable support for the ball bearing 20 ofthe vertical shaft 22. Shaft 22 is connected to the cylindrical rotor 2|which is provided with four equally spaced vanes 23 at one edge of theopenings or windows in the rotor. These vanes 23 are preferably at anangle of 45 degrees with a radius from the center of the 60 cathode.

The circuit connections for this device are more clearly illustrated inFig. 3. The anodes or plates it are connected by wire 25 to one terminalof the secondary of the energizingtransformer l 4 and transformer I 4 tothe plates It so that they arethe other terminal of which is connectedto the cathode sleeve.

When a suitable potential is applied from the at a higher positivepotential with respect to the cathode and the heater 6 is energized sothat the cathode surface is active, radial streams of electrons aregiven ofi from the surface 5 which move with increasing velocity towardsthe anodes or plates l6. Many of these electrons in seeking to reach theanodes impinge upon the surfaces of the vanes 23, thereby impartingrotation to the rotor 2| which supports the vanes. the power derived isdependent upon the number of electrons emitted in a unit of time, andalso upon their velocity it is preferred to employ a cathode having alarge active emitting area and to impress a high potential upon theanodes l6. Where the device is to -be operated as a power electrondischarge the envelope I will be evacuated; to a very low pressure suchas ordinarily employed in'present day. audions and similar spacedischarge devices. -It will be understood, however, that it is inaccordance with this invention to employ a gas or vapor filling withinthe envelope such as mercury vapor, so as to increase the number ofelectrical particles striking the vanes.

By reason of the construction above described, and the use ofalternating current as the energizing source for the anodes, the rotormoves at synchronous speed. Assuming that the current of the sour hasthe form illustrated in the upper curve f Fig. 5 anda trequency of 60cycles per second, 1 will be apparent that as soon as the rotor comesupto speed it will operate it synchronously. Since the current flowthrough the device is in one direction only, namely from the areutilized to project the electrons against the.

vanes 23 andconsequently each positive half wave will tend to get eachof the slots or windows opposite to one of-thesector units It. Thus, inthe example illustrated-where four anodes and four circuits areemployed, the motor will run synchronously at 900 R. P. M., assuming a60 cycle alternating current energizing source for the anode segments.While any desired width may be given to the windows in the rotor, it ispreferable to make them of the same angular width and likewise theanode'segments of the same angular width. The relationship may thenbe'expressed generally that if there are.n windows and n'anode segmentsand F is the frequency in cycles per minute of the energizing source,then the rotor member will revolve at R. P. M. 11

, by way of illustration since their numbers may be varied in accordancewith known'principles to cause the rotation of the rotor synchronouslyat other speeds.

This principle has been illustrated in the diagram of Figure 4 wherethere are but two anode segments l6 and I6, and where the rotor 2| hasbut one window and oneyane 23. In this case the similar segment I6 isconnected by wire 21 to one terminal of the secondary l4 and the otherterminal of which is connected by wire 28 to the cathode. With a deviceof this nature Since cuit during the starting of the motor.

'it is necessary to provide some form of starting means for bringing therotor up to synchronism. This is illustrated by means of the wire 29including a normally open switch 30 which connects wire 21 to anode Hi.When switch 30 is closed both anodes l6 and I6"- are energized from thealternating current source and the motor is then enabled to quickly comeup to speed in accordance with known principles. As soon as it reachessynchronous speed switch 30 may be 10 opened and the motor will thencontinue to run at synchronism, because every time anode- I6 becomespositive, the rush of electrons to it from the cathode strike the vane23 imparting impacts to the rotor in synchronism with the fre- 15 quencyof the energizing source.

While Fig. 4 shows a single phase and single anode motor, .it will beunderstood that the principle of connecting all of the anode sectorstogether applies to any other arrangement as illustrated for example inFig. 3. Likewise for starting purpose an additional set of anode sectorsmay be provided between the sectors it which latter sectors are onlyswitched into cir- The velocity of the electrons from the cathodetowards the anodes may be increased in accordance with well knownprinciples by the introduction of a control grid 24 between the cathodeof the rotor as illustrated in Fig. 3. In accordance with knownprinciples-in the operation of audions the control electrode may bemaintained at a potential positive with respect to the cathode wherebythe velocity of the electrons may be increased. 35

From the above description it will be apparent that this inventionresides in certain principles of construction and operation which may beembodied in other physical forms without departure from the scope of theinvention. I donot, therefore, desire to be strictly limited to thedisclosure as given for purposes of illustration, but rather to thescope of the appended claims.

What I seek to secure by United States Letters Patent is:

1. In combination an electron emitting cathode, a rotor to be rotated byemitted electrons, means for causing said'rotor to rotate under controlof said electrons, and means for controlling the starting of said rotor.

2. A synchronous electron motor comprising a container, an electronemitting cathode, a plurality of anodes surrounding said cathode, a 1'0-tor interposed between the cathode emitter and the anodes, means forenergizing the cathode emitter, and means for impressing alternatingcurrent potentials upon said anodes whereby the rotor is operated atsynchronism.

3. A synchronous electron motor comprising a container, an electronemitting cathode, a plurality of anodes surrounding said cathode, arotor interposed between the cathode emitter and the anodes, means forenergizing the cathode emitter, means for impressing alternating currentpotentials upon said anodes whereby the rotor is operated atsynchronism, and means for bringing the rotor up to synchronous speed.

4. A synchronous electron motive device comprising an envelope, acathode emitter mounted within said envelope, a plurality of anodessurrounding said cathode emitter, a rotor interposed between the cathodeemitter and the anodes, and means for impressing an alternating currentpotential upon the anodes.

5, A synchronous electron motive device coming all of the anodestogether for starting and bringing the rotor up to synchronous speed.

6. A synchronous electron motor comprising,

an envelope having a low pressure therein, -a

cathode emitter within the envelope, means for heating said emitter, aplurality of anodes surrounding said emitter, a rotor rotatablysupported between the emitter and the anodes, and means for impressingan alternating current potential upon the anodes.

7. A synchronous electron motor comprising an evacuated envelope, acathode emitter within said envelope, an anode within said envelope, a

rotor supported between the anode and the cathode, means for' applyingan alternating current potential to the anode whereby electronstraveling from the cathode to the anode strike the rotor and cause it.to revolve at synchronous speed, another anode, and means for applyingan alternating current potential to said second anode during starting.

8. A synchronous electron motor comprising an envelope, a cathodeemitter within the envelope, a plurality of anodes surrounding saidemitter, an apertured rotor supported between the emitter and theanodes, vanes mounted on the rotor at the apertures, and means forapplying an alternating potential to the anodes.

9. A synchronous motor comprising an envelope, a cathode emitter withinthe envelope, an anode, a rotor positioned between the cathode and theanode, means for applying an alternating current potential between thecathode and the anode, an auxiliary electrode and means for positivelybiasing the auxiliary anode with respect to the cathode during startingof the motor.

B. DU MONT.

